The flat panel display elements possess many merits of thin frame, power saving, no radiation, etc. and have been widely used. The present flat panel display elements at present mainly comprise the Liquid Crystal Display (LCD) and the Organic Light Emitting Display (OLED).
An OLED possesses many outstanding properties of self-illumination, no requirement of backlight, high contrast, ultra-thin, wide view angle, fast response, applicability of flexible panel, wide range of working temperature, simpler structure and process. The OLED is considered as next generation flat panel display technology.
An OLED display generally comprises a substrate, an anode located on the substrate, an organic emitting layer located on the anodes, an electron transport layer located on the organic emitting layer, and a cathode located on the electron transport layer. As working, the Hole and the Electron from the cathode are injected to the organic emitting layer, these electrons and the holes are combined to generate excited electron-hole pairs, and the excited electron-hole pairs are converted from the excited state to the ground state for achieving illumination.
In the present production procedure of the flat panel display, the Mura (uneven brightness) often happens due to the reasons, such as the production processes, and a bright spot or a dark spot appears to lead to the display quality descend of the panel. Demura is a technology of eliminating the display Mura and making the image brightness uniform. The basic principle of the Demura technology is: making the panel show the gray scale image, and using the Charge Coupled Device (CCD) to capture the screen to capture the brightnesses of the respective pixel dots in the panel, and then adjusting the gray scale values or voltages of the pixel dots of the Mura area to make the over dark area become bright and to make the over bright area become dark to achieve the uniform display result.
As applying Demura technology in the practical production, not only good display result is requested but also the time needs to be short. It requires great and practical Demura algorithm. The Demura algorithm used in prior art is to estimate the gray scale value after correction according to the Gamma value and the target brightness. As the method of eliminating Mura of liquid crystal display disclosed in the patent CN201310695713.X, which the specific steps are: first capturing the actual brightness values of the respective sub pixels, and correcting the actual brightness values of the respective sub pixels according to the brightness correction coefficients, and then, calculating and obtaining the gray scale values after correction corresponding to all the sub pixels of the inputted image according to the brightness values and gamma values of the respective sub pixels, and the specific calculation formulas is
            X      ⁢                          ⁢      1        =          L      ⁢                          ⁢              1                  1          Y                      ,wherein L1 is the brightness value after correction, and X1 is the gray scale value after correction, and Y represents the Gamma index.
In the OLED display panel, the difference of the gamma curve of the respective pixel dots, and particularly in the Mura area is larger. The expected compensation result cannot be realized with single calculation according to the unified gamma value or gamma curve. Therefore, the present Demura algorithm is not suitable for the OLED display panel.